Fluid dispensers for use in kitchens for storage and dispensing of fluid sources, such as vinegar, soybean source, or cooking oils, such as peanut oil, olive oil, soybean oil, etc., are frequently used in the kitchens. As people are becoming more and more concerned about health problems related to the excessive consumption of the sources and the cooking oils, the dispensers with a metering function are becoming more and more popular. This kind of “metering fluid dispenser” typically comprises a storing compartment for containing and storing the fluid, and a metering compartment on top of the storing compartment for metering a certain volume of the fluid to be dispensed. To facilitate the metering, the metering compartment is usually made to be at least partially transparent, and graduations are usually provided on the wall of the metering compartment. A pump, either manually driven or electrically actuated, is usually provided to pump the fluid from the storing compartment into the metering compartment.
In the operation of such a metering fluid dispenser, the user pumps the fluid from the storing compartment into the metering compartment, by pressing a button for example, until the desired volume of the fluid has been pumped into the metering compartment. Then the fluid that has been pumped into the metering compartment can be poured out of the metering compartment through a nozzle thereof for use in cooking food, for example.
A problem associated with this kind of metering fluid dispenser is that the fluid can only be pumped from the storing compartment into the metering compartment, but not the other way around. In other words, the fluid is not allowed to flow back into the storing compartment. Therefore, if a larger volume of fluid than desired is accidentally pumped into the metering compartment, the excessive amount of the fluid needs to be poured out of the metering compartment and be discarded, resulting in waste of fluid and inconvenience in the operation of the fluid bottle.